Apparatus for dispensing gas material



container. .andigthe y.consuming system is. idle lfor an appreciabley ,U 2,908,145 Arr-ARaTUs FoR DIsPENslNG GAs MATERIAL United States Paten-tf Haumanm Kenmore,;N.Y., assignorto Union j l Carbide, Corporation, a corporation of New York Application-March 25, 1957,SerialNo. 648,395`

" 1.1. claims. (C1. 62,-51)

Thisinvention relates to-a method of andA apparatus i.fon storingK and. dispensingI low-boiling liquefied gases;

'.laWaboilingfgases. may bedeinedas -those having boiling @pints att-,atmospheric pressure below- 2309 F., suchas oxigna Iaridlnitrogen, for example. More. particularly, it. concerns-fan, improved` method and apparatusfor deliveringgsuch materials 1in gaseous-form-from liquid stor- .raggi-ready.for-.immediate use.- atl superatmospheric pressore.

Insuiatedfconvertersare commonly employed for re- 2t.iving, gaA lowltemperature liqueliedl gasand vaporizing ,andladispensing-.the gasat a controlled superatmospheric GBFPSSUVIe. `These converters mustqalso serve as. highly Y etetivefstorage-.vesselstoconserve the liqueed gasduruiuggextended'periods oftime inzwhich there, may. beno dispensing-,ofthe-contents;. Since the liquid chargedinto .theserconvertersf is1-normallyv saturated; (in l thermal:r equiwithgits'fvapor) withfrespectto-a1ow;delivery.

pressnrejspecialprovisions; are neededto imposefand maintain a. higher nonequilibrium pressure suiiicient` for thegneeds. of the.- consuming; system..v Some prior. converte sgzhave.y withdrawn liquid frein` a lower` region,l of

theflcontainer.Y under the gravity head of liquidzwithin-the container in orderthata pressure lbuilding vaporizer, may receive, 'liquid by.v gravity liowy regardlessnoffthev pressure existentyinrthe vessel.v Pressure building must'v then be controlled bypa.; valvensually` locatedl. in theV vaporf recirouit :toi the.; vessel. for this purpose is leak-tight, thepressu'reV buildingsysv'term-.annotz bes. completely inactivated due to the con- .stanb4 driving forceappliedf by. Ithexstored liquidk in the Iii-valve leakage occurs in such converters Aperiod-3 of:tir`r1e,.excessive pressures willwbe'generated as al'fresulti of Athedncomplete.dead-ending of the pressure Other-earlier. convertersnhave employed a small ex- 4tornai-pressure.building chamber: sepa-rate from and;

above the converter container andihave thereby eliminated thecconstantly applied-driving force-ob the stored lquihi` Suchchambers were fedby the over-'toplwith- -drawall oliquidtfrom. thefconver-ter under.y a pressure `diererrtiaia created: by. YventingV gasI from. -the chamber.kk

y(Qtl.1 r;.centinuously.' or4 intermittently) toV theatmospheree Suche-venting: of gas is wasteful andiexpensive and@ precludes, making an accurate; yaccounting ofly Ithe ..matrialgstoredfandidispensed. The arrangementis not ,alpqsitiye solution,to.the problem since the valve. which.

is grequiredfor, controlling., the chamberrvent; may leak andi thereby-permit; continuous and unwanted pressure :'.bllldinge I. 'Furthermqrta prior. `converters .have -usually employed `-.312 @Sironepotherigcontrol.valveand often two, for. the.,

Unless. the valve .employed fbe'agsifively- 'inativated Without; depend ICC . 2.V y ence4 uponV the leak-tightness of a' control: valve. Also, complete control of -both` pressure: building.r and consumer .withdrawalacan be. accomplishedin thissystem by. only la singleautolmatic con-trok.

Itis therefore. the principal. object: of .this invention to'provide a systemfor storingfand.: dispensing. liquefied gases which employs simplied: and more dependable automaticA controls, `and permits`v the. .consumen to@ Withdraw material from.- =the. `container with; an minimum amount of attentiveness .and skill on `his part.

A more particular objectief` theinvention is to provide a converter for'storing low-boilingv materials in liquefied formand for dispensing lsuch materials ini gaseouswform, which is provided with. an. automatic pressurefbuilding and vaporizing system. l

These andv other objects, features..andhadvantages:of thepresentinvention will become apparent from the -fo1- lowingdetailed description ofzthe. accompanyingdrawings' in which:

Fig. l' is avertical. transverse section. through a container embodying the systemof the. present invention; and Y Fig. 2is la fragmentary. vertical section of= alcontainer similar. to that shown in Fig. l; but illustrating armadiiied form of gas withdrawal system. l Y

As shownI in the. drawings: a `customer containerifor converter 16 provides a. unique system fordispensingin gaseous form and'at` apredeterminedservice. pressure materialwstoredin liquidphase. Customer serviceeiszinauguratedsimply by'connecting. service line. 60 toithe customers line v.(not shown)said customers linen-usually havinga pressureregulating valve1therein. The service line. 6.0. is conneotedzthroughi a..vaporizing coil; 641Vv disposed between the .converter casing.- 17 and. an inner. vessel. 18. with both the .liquidi and .gas phases .ofthe-vessel 181-. The liquidl phase connection, an eductionitube7f66, f

passes from .a point: near theA bottomof thel:vessel;18'up wardly to a loop. 681where it is reversely benttto .extend downwardlyl to a line iwhich' leadsradially. outwardly to .a T.junction z 7 2. interconnecting. the `liquid i withdrawal line,'.the gas withdrawalline 74"and a line..76 leadingito theY inlet end ofthe.: vaporizing` coil 64.". Tliegasiwithdrawall line 74.is connected with thezgasl. phase oftthe vessel ythrou-gh a back pressure controller, or.` gas-'ow regulator 78, which is preferably disposed inz the.head ofzthe converter 16; Regulator-78. includes-a chamber 811 which is open to thegas space. of thevvessel: 18 through. a.passageway. 82iand has 'a'.vfalve'. p1ungerl84 which Yis .connected withwa .bellows 86 and which .is normally urged toward4 a closedpostion by: a'compression spring 88=acting on oneside of the bellows. Thezother side of the bellows isf. subject topressurein theggas space; whichopposes the spring andi-will act .tofliftuthe plunger 84.when vesselpressure exceedsfthets'ettingof the regulator, thereby opening-.the gas space `tothesservice. 'connection .602through the regulator 78; lines=74 and 76 and the coil 6.4. Thus,` wheneverpressuref'inithevessel 181y exceeds the setting ofthe regulatorxbecause of evaporation"A due torheat leak, theregulatonopens 'and remains openuntil the pressure falls belowI such. setting. if. vessel pressurev is.above:the setting at the initiation of a withdrawalperiod orwbecomes so duringwithdrawal period, withdrawaly automatically. takes y piaceelfroms-.the gas phaseiof the .vesseluntil pressure in thei-.vesseliial-ls slightly belowthesetting: of regulator 78;

Line 76 leading" to the coil 64; is branched z aboubat the` normal full liquid level.' at: another?. T-junctionz-or interconnection j Aline-92.; extends' from thisrappint vertically downwardl .to .a check .valve :94v at zonerendfoff` a vaporizing coil 96.` forrnin-gyjpartE off ia .means :for@.huild ing,- 'and maintaining ;a pressure in the-vassel-ltlaati-a 'stantiallyr4 `cnstarit value dwing withdrawal forF leffecting delivery of the liquid phase material to the vaporizing coil 64 for delivery to the service connection 60 at the desired substantially constant pressure, The inlet por- ,ation of/vaporizercoil 96 is locatedbelow the'level `of '.'theffliquid ingthe vessel 18, andpreferably below the ,lowest point zon thebottorn of vessel :18V as shown in Figure 1. A vapor return line 98v leads from the other :,endaof coil 96 .to the top part of vessel 18. yfor 'delivery vof vaporizedV material into the .gas space for buildinga .non-.equilibrium pressure therein. l .Y Operation yof the pressure building lsystem is automatic,land gas will ybe generated.' for pressurel=building whenever liquid is available inline 92. Avunidirectional flow device such as check valve 94 acts to prevent backow of vapor from the vessel gas space to the customer through the pressure building circuit and to prevent the vapor generated in the pressure building coil from flowing back to the customer rather than to the -gas space of the vessel. As an alternative to the checkvalve, line 9.2 may be extended in the form of Van elongated liquid cation with, the outer Wall of the container." The upevent the container is overiilled. Thus, if, the container is overlled, residual liquid inthe coil 64 at the termination of a withdrawal vaporizes `and expands, or residual gas lin the coil 64 expands, and the gas under pressure forces liquid kin .the down sideof the loopptjjbaclgfup over the ltop of the loop and forms a gas trap to prevent liquid feeding into theY relatively warmfvapbriziiigboils 64 and 96.` Otherwise, if 'thetop of -the eduction tube were below theV liquid level in an overiilled condition', liquid would feed into the warmcoilsand force warm gas back intothe container, thereby V'adding undesired heat to the container.

It will be noted that liquid ows from container 18 only through a withdrawal line extending upwardlyfrom the bottom of the vessel to a height'above-thefnormal full liquid level. A conduit, gravity-fed with liquid fr'ifn wardly extendingV Ilegs of .such a trap would continue connection 90, to the pressurebuilding vaporizer, but" vapor cannot normally return through ,-therline toY connection 90 `due to the liquid seal maintained in the trap. When a customer desires to make -a withdrawal, `the opening of the service `connection to a demand estabalishes a pressure differential between lineV 60 and thev interior of the lvessel 18. If the pressure vin the gas `space exceeds the setting of regulator 78, withdrawal -takes place from-theY gasrphase as described above. If

vessel pressure is below the setting of the regulator, the- I established pressure differential causes liquid to be forcedV `up through the eduction line 66, over .loo-p 68, down f through lines 70 and 76, and into the vaporizer coil 64. .At the, same time, the ilow of liquid Vinto line 76 Aalso the withdrawal line, is connected outside'the'fin'ner vessel to the inlet of pressure builder 96. Thus, the force orV the liquid head exerted by gravity on thefipres- -sure builder is'only that liquid inthe downwardly eirtending portions of the withdrawal line Y andl feed-conduit,

` and this liquid head can be applied or-completelyremoved at will by a single control valve. The overtop withdrawal of 'subcooled liquideforA both pressure building and dispensing'purposes-in thisilnfiqe manner is critically dependent uponthe inaintenance'bf non-equilibrium pressure in container- 18 Vat'alli-tirnes.

v'We have discovered that non-equilibrium pressure can be rmaintained in stationary converters withoutvpres'sure Athe colder liquid entering the container.

building over indeiinite periods of idle storage.- During iilling operations, proper precaution must' -be'talefto avoid excessive condensation of pressurizing' vapor "in A"sitable method of manually controlling the pressure during'filling 'results in the filling of 'vertical line 92 between inter-f` connection 90 and check valve 94. The head thus estab'- *lished in line 92 provides v`a driving force for operating --the pressure building system (i.e. liquid ilows under they force of this head into thecoil 94, is vaporized and retion the flow of liquid between gas phase and liquidph'a'se turns as gas through line 98 to the gas space ofV the,

is described in U.S. Patent 2,368,215 to O. A. Hansen.- Alternatively, automatic pressure control while filling the converter may be obtained as shown in Figurelbymens of aiilling line 99a provided along its length' \inside"the container with small holes or slits 99; The holesfbr slits are properly sized and distributed in order toproporentryY in such manner that the container :pressure vremains reasonably steady.

By means ofthe dispensingLarrangementiwhich'hs been described herein, a relatively simple and automatic converter is'obtained which has a minimum number of vz bility, 'and which allows the customerto withdraw gas at the vertical lineto pass liquid in such line to both thev i vaporizing `coil 64 and to the pressure building Vaporizing -coil 96 through check valve 94. This however could require -a larger line to accommodate both the vaporizer f and pressure building coil liquid flows. The larger line Y. would hold more liquid which must, at the termination Aof a iliquid withdrawal period, drain through the pressure building coil 96, thereby resulting in a less desirable,v

\ largerpressure override in the vessel 18.

If container pressure reaches the 'setting ofthe regulal tor 78 during liquid withdrawal, valve 84 opens. When .this Valve opens, the pressure drop between intercond nection 72 and the gas space is lower than the pressure drop across lines 66, 68 and 70,1liquid flow is terminated, and further withdrawal takes place fromthe gas moving parts, providing reliability andgreater'dependawill without attention to, or control of, 'the converter.:

It should be apparent however that various detailsi'of y construction can be changed without departing from the phase. Since liquid is no longer available `at the intera,

connection 90 for `delivery into line 92, the pressure l'building systemwautomatically ceases to function until the pressure in the vessel falls below the setting of the regulator 78 to effectfclosing of valve 84. In `order to "insure against continued withdrawal of liquid when valve 84 opens,'the junction point 72 must beat a level near or preferably abovejthe normal full liquid level ,of the `container so -that any Siphon action that might lothewise spirit of this invention as dened in What is claimed is: l. Apparatus for dispensingl the appended claims.

a heat-insulated container for holdingvsuch liquee'd gas material undera predetermined superatmosphericpressure; a service connection for consumption apparatus yhaving a vaporizer therein; a liquidV withdrawal linefextending upwardly from one end at a lower'reigio'n offthe container to above normalull liquid lev'eltfof thefcontainer and being connected at its other vendhto saidservice v A'120 provide a free ilow passageway between the `low of the container` and the service connectionw'so can pass freely-through lsaid withdrawal line-v tos d servv ice connection whenever a pressure 4diirence exist'sacross the liquid withdrawal line that at'leastjequalf, 4 the flow resistance therein; a gas phase withdrawliline o nnecting the upper region of the container above the nrmal full liquidlevel with'theyliquid withdrawallne at a point above said level; Yvalve means in/saidI 'gas'fph'a'se in gaseous form a lowboiling gas material stored in liqueiied form, comprising n en line being normally closed but responsive to container Pressure so as tojopen the 'topiregionof the container to ythe service connection when the pressure insaid conjtainer rises .to a desired value above said predetermined pressure and cause material'to be Withdrawnin gas phase from the top ,region ofthe container; and pressure building means for maintaining pressure in said container comprising an external fluidcircuit' having a feed' line convne.cted .atone end with the liquid withdrawal line at; a

point sucnthat. liquid from the withdrawal Iline liows, into the feedline by gravityLa vaporizer connected with drawalline to.the vaporizer but restricting fluid llowin a direction from the upper region ofthe container to the,

n liquid withdrawal line.

3.-Apparatus forY dispensing in gaseous forma lowboiling/gas material storedin liquefied formLcomprising a `heat-insulated container` for holding such liquefied gas material under4 a predetermined superatmospheric pressure; a service connection for consumption apparatus having a vaporizer, therein; aliquid withdrawalline extendingupyvardlyfrom one end at a lower regionvof the container to above .thenormal'fullliquid level of the containerjand being connectedat its other end to said service.

connection, said liquid withdrawal line being open to provide'a free. flow passageway between the lower region of'the container and the service connection so that-liquid can; pass freely. through said' withdrawal line `tot said service connection whenever a pressure diiference exists.

'across theliquidwithdrawalline that is at least equal vtcnilow lresistance therein; a gas phase withdrawal line yco'nnectinguthe upper region of the container above the A normal full liquidA levelwith the liquid withdrawal'line Y at a pointab'ove said level; valve means in said gas phase4V line beingdnormally closed4 but responsive to container pressure so as to open the top region of the container to .the service connection when the pressure in said con- 'tainer rises toa desired'valuegabove said predetermined I pressure and thereby terminate liquid withdrawal froml the. lower regionofv the containerandinitiate Vgas withdrawal from the top region of the container; and pressure Vbuilding meanswfor maintaining pressure in said container comprising an external fluid circuit having a feed line connectedat one e nd with the liquid withdrawal line at l a p oint such that liquid from the withdrawal'line flows Tinta thefeedlineby gravity, a vaporizer connected with the other end of the feed line and positioned to receive liquid from said feed lineunder a total gravity head of liquid atleastrequalto the height'of liquid'y in said con tainer, and a return line for passing vaporized material from such vaporizer to-thecontainer above the normal full liquid level; said externalV huidl circuit containing therein unidirectional flow means positioned to permit nid flow in a direction from the liquid withdrawal line to the vaporizer but restricting :duid flow in a direction from the upper'region of the container to the liquid Withdrawal line.

4. Apparatus for dispensing in gaseous form a lowboiling gas material stored in liquefied form, comprising a heat-insulated container for holding such liquefied gas material under a predetermined superatmospheric pressure; a service connection for consumption apparatus having a vaporizer therein; a liquid withdrawal line having a first, upwardly extending leg leading from a lower region of the container to above the normal full liquid level of the container and a second leg extending downwardly to a lower region of the container and being connected at its lower end with said service connection; said liquid withdrawal line being open to provide a free ow passageway. between thelower regionof the container and lthe service connectionso that liquid canpass freely through said withdrawallineto the service connection whenever a .pressure difference exists across theliquid withdrawall line that isr'atI least, equal' to .ilow resistance therein; agasphasewithdrawal line connecting theuppler region ofthe container4 above the normalfullliquid level withthe liquid withdrawal line at a point abovesafid leveljvalve means in said'gas line beingmormally closed b ut responsive to container pressure so as to open the toplregion of the container to the service connection when the pressure in said container rises to a desired'value above said' predetermined pressure and cause materialfto bewithdrawn in vapor. phase from the topregion ofthe container; and pressure building means for maintaining pressure in, said container comprising an externa'hfluid circuit havinga feed'line connected at one end'with the j liquid withdrawal line at a point such that liquidlf'rom the withdrawal lineflows into thefeed'line by gravity, a

vaporizer connected withthe other end of said feed' line d and dsposedat alower region of the containerto receive liquid. therefrom under gravity flow,- andare'turnline for passingL vaporized material in such vapori`zer tol the container, above the normal full liquid level.

5. Apparatus as deiined'in claim 4, wherein said feed y lineis connected with s aidliquid withdrawal lineatabout the normal fullliquid levelso as to` establisharelatively constant head on the pressure bfui-ldingvaporizer throughout thewithdrawal period.V f

6. Apparatus as deiined in claim 4, wherein said feed line is connected with saiddownlwardlyextending leg of i the liquid withdrawal line in thevicinity ofthe lower, end

th'ereofso asto utilize theliquid headin said downwardly extendinglegto serve as the driving force for thepressure building circuit.

7..Apparatus fof dispensing in gaseous form a lowboilinggas material'stored in liquefied form, comprising ahem-insulated container for holdingsuch liquefied. gas

materiahunder a predetermined superatmospheric, pressure; a,service connection for consumption apparatus havinga vaporizer therein; a liquid withdrawal line "extending from oneendat aflowerv regionof the container upwardly to `abovethenorinal full liquid level of the container andbeingprovidedwith' areversely bent loop, lthe 5 talner; saidy llquidwithdrawal line `also havmgy a portion bight'of whichl lies,at a level near the, top of the c onleadingfrom the other ,end 4of the loop to said service connection, said liquid :withdrawal line being open toprof vide afreeflow passageway between the, lower regionof the container and theservice connection so that liquid ca-nV pass freelyfthrough said withdrawal line to s-aid service. connection whenever a pressure diiierence4 exists across the liquid withdrawal line that is at least equal to flow resistance therein;,a lgas phase withdrawallineconnectingytheupper regionofthe container above thefnorni-alfull liquid level with the liquidwithdrawal line at a point above-said level; valve means in said gasphaseline beirigmnonnallyJ closed but responsive to container -pressure;so.as to openthetop region of the container,to the service connection when the pressure in said container rises to a desired value above said predetermined pressure and cause material to be withdrawn in gas phase from the top region of the container; and pressure building means for maintaining pressure in said container comprising an external fluid circuit having a feed line connected at one end with the liquid withdrawal line at a point such that liquid from the withdrawal line flows into the feed line by gravity, a vaporizer connected with the other end of said feed line and positioned to receive liquid'therefrom under gravity, and a return line for passing vaporized material from the vaporizer' to the container above the normal full liquid level.

8. A process for converting a low boiling liquefied gas to gaseous form and for delivering gas at a predetermined elevated pressure to a withdrawal connection in response f lto a'dernand for gaseous materiaL'cornprising' providing `v'an `insulated container under said predetermined elevated 1 -pressure with liquid saturated with respect to a pressure substantially lower than said predetermined pressure, con- `y ducting liquid from a lower region of the container vto an` upper region above the normal full liquid level in .the

[container under a pressure differential established between the existing container pressure andthe pressure in the withdrawal connection when the latter is opened to supply a demand for said material, vaporizing said liquid for delivery to consuming means, conducting additional ffliquidunder said pressure differential from a lower region fof the 'container to an upper region above the normal full liquid level in the container, further conductingsaid yadditional liquid downwardly by gravity flowvthrough a height at least equal tothe height of liquid in said container, L vaporizing said additional liquid and passing the Vaporized additional liquid to the upper region of said container above the normal full liquid level to maintain non-equilibrium `conditions in the container at said predeterminedl pressure; and at container pressures exceeding said pre.- determined pressure, opening the upper region of the container to the withdrawal connection at a point above the normal full'liquid level therein so that said pressure dif. i vferential between said container pressure and the pressure in the withdrawal connection is reduced to a value below that required for said conductings of liquid and additional liquid, thereby terminating said conductings of liquid and additional liquid and initiating the lrlow of gas from said upper region to the withdrawal connection.

9. A method of delivering low boiling gas material at a predetermined pressure from a source in which said material is stored both in liquid phase and in gas phase,

said liquid phase being under the pressure of the gas phase.

and saturated with respect to a pressure substantially lower than the pressure of said gas phase, conducting liquidfrom the liquid phase upwardly against'the force of gravity to a height at least above the normal full liquid f level of said source under va pressure diierential createdv between the 'pressure in the gas phase and the pressure in a withdrawal line by the existence of a demand for stored material, said -pressure d'ierential being suflicient to overcome said force of gravity acting on said liquid, passing at least Vpart of the liquid at such height into said v withdrawal line to meet said demand, utilizing Vthe added v potential energy ofthe liquid at such height to vdrive some of such liquid through a pressure building circuit i and to return vapor formed therein to said gas phase to increase the pressure thereof, and when the pressure of Vvsaid gas phase exceeds said predetermined pressure by a preselected amount, releasing vapor from said gas phase into the withdrawal line to control the pressure of theV gas phase.

said liquid phase being under the pressure of the gas phase and saturated with respect to a pressure substantially liquid `from 'the Yliquid phasefupwadiyjagainst e *te fof gravity to a height atleastfabo've th nor ai-ffailfiiqiiid' Ylevel of said source. under. a pressure differential 'created between 'the pressure in Athe gas phase-`ar1dthepressnre ina withdrawal line by the existence`V ofl alfdernndlfor stored material, said vpressure differential being sufficient ffandto return vapor formed thereln to said'jga'splaseito vl `increase thepressure thereof,- arid when? .the'pressurefpf the gas phase vexceeds said predetermined 'pressure 15,.

by a preselected amount, yreleasing gas from said gasphaseinto said -withdrawal Vline `at a point .above the .ncirfir'ral'` liquid levelof said source,ifthe'lreby terminating the. u ward conduction .of i liquid and.. preferentially delivering. gas *from theA gas phase to said Withdrawal line.W 20.

l1. Apparatus for dispensing a gaseous-form vlofwboiling gas material stored' in liqueed form,' lcompris'ing a heat-insulatedcontainer vfor holding such liqueiie'dgas .material under a predetermined superatmospheric, pres- "sure; a. service connection for4 consumption apparatus having a vaporizer therein; 'a liquid withdrawal linefextending upwardly. from one endat a lower. .1 egi on ,o he container to-above normal full liquid level' f 't he on tain'er and being connected'at its other end .tolsaidse connection, said liquid withdrawal line being openrto roor the container and the service connection so l' i canpass freely through said withdrawal. line to s` ds'erv- Videla free flow passageway betweenfthe lowe i `ce connection Whenever a pressure differenceixxists acrossthe liquid withdrawal line that is'aty least equal v to .the flow resistance thereima gas phasefwithdrawalfline connecting the upper region of thel container. aboyetlieV normal full liquid levelwiththe liquid withdrawalflirie; valve means Yin saidgas phaseline being normali,`A

but responsive to container pressure soas to ope-n .the top 40, l

nosed when region 'of the'container to the service` connecti fthe pressure in Vsaid container rises Vto ades'ire value above said predetermined pressurefandl cause nia be .withdrrfiwn"in` gas phase from :the topi regionlof Vhe container; and pressure building means fonrnain mng circuit. having a .feed lineconnected atA one .end" vvith'f the liquid'withdrawal line at a pointsuch Vtliatfliq'u the-withdrawal line flows into thefeedline by yg j vaporizer to the .containenabove the .normalfull l' lower than the pressure of said gas phase, conducting i 2,376,985 fwildhack' r;;

pressure in said container comprising..an external fluid from vaporizer connected with the otherend offsaid Af vand positioned'to receive liquid therefrom under yand a return line for passing vaporiz'ed materialfn alto 

